Various government regulations require that the average actual net weight of packaged or containerized consumer products, such as instant coffee, be equal to or above the labelled net weight of the products. To keep abreast of the demand for their products, manufacturers must utilize high speed filling machines which move the containers at constant speeds. Since only volumetric dispensing devices can be used to fill moving containers, and the labelled net weight must be close to the actual net weight even when the dispensed volume or the product density are at their lowest levels, manufacturers often overfill containers with considerable amounts of product as fluctuations in the density of the product and the dispensing volumes occur.
To eliminate such inaccuracies, it is desirable that the product be dispensed by weight into the container; however, accurate weighing requires a low rate of product flow which, in turn, requires long filling cycles. Ideally, to keep the length of filling time to a minimum, the containers may be first underfilled with the bulk of a product from a volumetric filling machine. Thereafter, these underfilled containers may be topped off with a small amount of product to bring the actual net weight to the labelled net weight in fairly short time cycle, e.g., under two seconds, utilizing low product flow in a machine dispensing by weight.
Since known weight dispensing devices cannot travel at high speeds and maintain their accuracy utilizing desirable low product flow rate, it has become necessary to perform the top-off dispensing operation from stationary dispensing devices. This permits an unimpeded flow of product into the stationary dispensing device as well as accurate weight control. With the containers travelling at a desired line speed, the containers must be decelerated to a stop underneath the dispensing device for the period of time necessary for the filling operation to be performed at a low rate of product flow, and then accelerated to restore them to their normal rate of line speed.
Conventional means employed to perform these deceleration/acceleration steps utilizes a reciprocating fork mechanism to decelerate the containers to rest under stationary dispensing devices, and then accelerate them back to line speed, the containers travelling in a straight line during the decelerating and accelerating. However, these mechanisms are incapable of operating in connection with high line speeds, even if they handle several containers simultaneously, since the mechanisms are large, bulky and required several time-consuming movements for proper positioning and removal of the containers in relation to the dispensing devices.